Latest ELISA on OpenSUSE Tumbleweed does not allow to switch output channels at all. The audio selector in KDE is always fixed to one device, you can not change this. Other applications (e.g. VLC) allow this selection. Bug was confirmed for different distros, see https://discuss.kde.org/t/elisa-wont-output-to-bluetooth-headset/43593 for reference
This could be due to the latest version of wireplumber (0.5.13 on Fedora 43). Try downgrading wireplumber and restarting your system.
Latest OpenSUSE Tumbleweed 20260126 also has wireplumber 0.5.13.2.1